Subarray‐based time‐delay low sidelobes methods for space‐time coding array

A space‐time coding array (STCA) system transmits an identical waveform with a small time offset across the array elements. It shares the characteristics of high angular resolution and instant wide angular coverage, leading to the low probability of interception as seen in the traditional multiple‐input and multiple‐output radar. Angle‐time two‐dimensional matched filter is required in the STCA. However, the sidelobe level (SLL) of the multi‐dimensional ambiguity function in the range and angle domains is not as low as that desired in practical applications and the range resolution decreases as the number of elements increases. Here, two kinds of subarray‐based time‐delay methods are proposed to improve the resolution and reduce the SLL of the ambiguity function for STCA. Both the regular and irregular subarrays are considered, which increase the degrees of freedom and thus enhance the range resolution. Moreover, the SLL of the ambiguity function is reduced. Simulation results are provided to demonstrate the effectiveness of the proposed methods.